/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***/

package net.wimpi.modbus.msg;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import net.wimpi.modbus.Modbus;

/**
 * Provides the a<tt>ModbusResponse</tt> implementation that represents a Modbus
 * exception.
 * 
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public class ExceptionResponse extends ModbusResponse {

	// instance attributes
	private int m_ExceptionCode = -1;

	/**
	 * Constructs a new <tt>ExceptionResponse</tt> instance.
	 */
	public ExceptionResponse() {
		// exception code, unitid and function code not counted.
		setDataLength(1);
	}// constructor

	/**
	 * Constructs a new <tt>ExceptionResponse</tt> instance with a given
	 * function code. Adds the exception offset automatically.
	 * 
	 * @param fc
	 *            the function code as <tt>int</tt>.
	 */
	public ExceptionResponse(int fc) {
		// unitid and function code not counted.
		setDataLength(1);
		setFunctionCode(fc + Modbus.EXCEPTION_OFFSET);
	}// constructor

	/**
	 * Constructs a new <tt>ExceptionResponse</tt> instance with a given
	 * function code and an exception code. The function code will be
	 * automatically increased with the exception offset.
	 * 
	 * 
	 * @param fc
	 *            the function code as <tt>int</tt>.
	 * @param exc
	 *            the exception code as <tt>int</tt>.
	 */
	public ExceptionResponse(int fc, int exc) {
		// exception code, unitid and function code not counted.
		setDataLength(1);
		setFunctionCode(fc + Modbus.EXCEPTION_OFFSET);
		m_ExceptionCode = exc;
	}// constructor

	/**
	 * Returns the Modbus exception code of this <tt>ExceptionResponse</tt>.
	 * <p>
	 * 
	 * @return the exception code as <tt>int</tt>.
	 */
	public int getExceptionCode() {
		return m_ExceptionCode;
	}// getExceptionCode

	public void writeData(DataOutput dout) throws IOException {
		dout.writeByte(getExceptionCode());
	}// writeData

	public void readData(DataInput din) throws IOException {
		m_ExceptionCode = din.readUnsignedByte();
	}// readData

	public String toString() {
		return "ExceptionResponse - Exception code: " + m_ExceptionCode;
	}

}// ExceptionResponse
